diff options
Diffstat (limited to 'src/core/execute.c')
| -rw-r--r-- | src/core/execute.c | 103 |
1 files changed, 97 insertions, 6 deletions
diff --git a/src/core/execute.c b/src/core/execute.c index 3c3369373f..8cb18dbd5b 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -1237,7 +1237,7 @@ static int apply_memory_deny_write_execute(const ExecContext *c) { r = seccomp_rule_add( seccomp, - SCMP_ACT_KILL, + SCMP_ACT_ERRNO(EPERM), SCMP_SYS(mmap), 1, SCMP_A2(SCMP_CMP_MASKED_EQ, PROT_EXEC|PROT_WRITE, PROT_EXEC|PROT_WRITE)); @@ -1246,7 +1246,7 @@ static int apply_memory_deny_write_execute(const ExecContext *c) { r = seccomp_rule_add( seccomp, - SCMP_ACT_KILL, + SCMP_ACT_ERRNO(EPERM), SCMP_SYS(mprotect), 1, SCMP_A2(SCMP_CMP_MASKED_EQ, PROT_EXEC, PROT_EXEC)); @@ -1264,6 +1264,76 @@ finish: return r; } +static int apply_restrict_realtime(const ExecContext *c) { + static const int permitted_policies[] = { + SCHED_OTHER, + SCHED_BATCH, + SCHED_IDLE, + }; + + scmp_filter_ctx *seccomp; + unsigned i; + int r, p, max_policy = 0; + + assert(c); + + seccomp = seccomp_init(SCMP_ACT_ALLOW); + if (!seccomp) + return -ENOMEM; + + /* Determine the highest policy constant we want to allow */ + for (i = 0; i < ELEMENTSOF(permitted_policies); i++) + if (permitted_policies[i] > max_policy) + max_policy = permitted_policies[i]; + + /* Go through all policies with lower values than that, and block them -- unless they appear in the + * whitelist. */ + for (p = 0; p < max_policy; p++) { + bool good = false; + + /* Check if this is in the whitelist. */ + for (i = 0; i < ELEMENTSOF(permitted_policies); i++) + if (permitted_policies[i] == p) { + good = true; + break; + } + + if (good) + continue; + + /* Deny this policy */ + r = seccomp_rule_add( + seccomp, + SCMP_ACT_ERRNO(EPERM), + SCMP_SYS(sched_setscheduler), + 1, + SCMP_A1(SCMP_CMP_EQ, p)); + if (r < 0) + goto finish; + } + + /* Blacklist all other policies, i.e. the ones with higher values. Note that all comparisons are unsigned here, + * hence no need no check for < 0 values. */ + r = seccomp_rule_add( + seccomp, + SCMP_ACT_ERRNO(EPERM), + SCMP_SYS(sched_setscheduler), + 1, + SCMP_A1(SCMP_CMP_GT, max_policy)); + if (r < 0) + goto finish; + + r = seccomp_attr_set(seccomp, SCMP_FLTATR_CTL_NNP, 0); + if (r < 0) + goto finish; + + r = seccomp_load(seccomp); + +finish: + seccomp_release(seccomp); + return r; +} + #endif static void do_idle_pipe_dance(int idle_pipe[4]) { @@ -1951,10 +2021,20 @@ static int exec_child( int secure_bits = context->secure_bits; for (i = 0; i < _RLIMIT_MAX; i++) { + if (!context->rlimit[i]) continue; - if (setrlimit_closest(i, context->rlimit[i]) < 0) { + r = setrlimit_closest(i, context->rlimit[i]); + if (r < 0) { + *exit_status = EXIT_LIMITS; + return r; + } + } + + /* Set the RTPRIO resource limit to 0, but only if nothing else was explicitly requested. */ + if (context->restrict_realtime && !context->rlimit[RLIMIT_RTPRIO]) { + if (setrlimit(RLIMIT_RTPRIO, &RLIMIT_MAKE_CONST(0)) < 0) { *exit_status = EXIT_LIMITS; return -errno; } @@ -2015,7 +2095,7 @@ static int exec_child( } if (context->no_new_privileges || - (!have_effective_cap(CAP_SYS_ADMIN) && (use_address_families || use_syscall_filter))) + (!have_effective_cap(CAP_SYS_ADMIN) && (use_address_families || context->memory_deny_write_execute || context->restrict_realtime || use_syscall_filter))) if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) { *exit_status = EXIT_NO_NEW_PRIVILEGES; return -errno; @@ -2037,6 +2117,15 @@ static int exec_child( return r; } } + + if (context->restrict_realtime) { + r = apply_restrict_realtime(context); + if (r < 0) { + *exit_status = EXIT_SECCOMP; + return r; + } + } + if (use_syscall_filter) { r = apply_seccomp(context); if (r < 0) { @@ -2472,7 +2561,8 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) { "%sProtectHome: %s\n" "%sProtectSystem: %s\n" "%sIgnoreSIGPIPE: %s\n" - "%sMemoryDenyWriteExecute: %s\n", + "%sMemoryDenyWriteExecute: %s\n" + "%sRestrictRealtime: %s\n", prefix, c->umask, prefix, c->working_directory ? c->working_directory : "/", prefix, c->root_directory ? c->root_directory : "/", @@ -2483,7 +2573,8 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) { prefix, protect_home_to_string(c->protect_home), prefix, protect_system_to_string(c->protect_system), prefix, yes_no(c->ignore_sigpipe), - prefix, yes_no(c->memory_deny_write_execute)); + prefix, yes_no(c->memory_deny_write_execute), + prefix, yes_no(c->restrict_realtime)); STRV_FOREACH(e, c->environment) fprintf(f, "%sEnvironment: %s\n", prefix, *e); |